Question

$K_2Cr_2O_7$ paper acidified with dil. $H_2SO_4$ turns green when exposed to :

• A. $SO_2$
• B. $SO_3$
• C. $CO_2$
• D. $H_2S$

Answer 1

Answer: (A)

$SO_2$

Answer 2

$SO_2 \text{ } \text{ } \text{ } \underset{H^+}{\underset{\longrightarrow}{K_2Cr_2O_7}} \text{ } \text{ } \text{ }\underset{(green)}{Cr^{3+}} + SO_4^{2-}$

The correct option is (A): $SO_2$